lxc-monitor has an option to tell lxc-monitord to quit.

```
~/lxc (master) # lxc-monitor --help
lxc-monitor monitors the state of the NAME container

Options :
  -n, --name=NAME   NAME of the container
                    NAME may be a regular expression
  -Q, --quit        tell lxc-monitord to quit
```
But it does not work. This patch fix that.
Signed-off-by: 0x0916 <w@laoqinren.net>